Predicting Weather Using a Barometer and Wind Direction

Wind/Barometer Table

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Use a barometer to forecast wind direction and the character of upcoming weather.

Here are some general statements of wind-barometer indications that are generally applicable to all parts of the country:

When the wind sets in form points between south and southeast and the barometer falls steadily, a storm is approaching from the west or northwest, and its center will pass near or north of the observer within 12 to 24 hours, with wind shifting to the northwest by way of south and southwest.

When the wind sets in from points between east and northeast and the barometer falls steadily, a storm is approaching from the south or southwest, and its center will pass near or to the south of the observer within 12 to 24 hours, with winds shifting to northwest by way of north. The rapidity of the storm’s approach and its intensity will be indicated by the rate and amount of the fall in the barometer.

As a rule, winds from the east quadrants and falling barometric pressure indicate foul weather, and winds shifting to the west quadrants indicate clearing and fair weather, but again there are exceptions and in some parts of the country these rules do not apply.

The following table generally summarizes wind and barometer indications in the United States. The amateur forecaster should modify the table in accordance with his or her own observations.

Wind/Barometer Table

Barometer(Reduced to Sea Level)

Wind Direction

Character of Weather Indicated

30.00 to 30.20, and steady

westerly

Fair, with slight changes in temperature, for one to two days

30.00 to 30.20, and rising rapidly

westerly

Fair, followed within two days by warmer and rain

30.00 to 30.20, and falling rapidly

south to east

Warmer, and rain within 24 hours.

30.20 or above, and falling rapidly

south to east

Warmer, and rain within 36 hours.

30.20 or above, and falling rapidly

west to north

Cold and clear, quickly followed by warmer and rain.

30.20 or above, and steady

variable

No early change.

30.00 or below, and falling slowly

south to east

Rain within 18 hours that will continue a day or two.

30.00 or below, and falling rapidly

southeast to northeast

Rain, with high wind, followed within two days by clearing, colder.

30.00 or below, and rising

south to west

Clearing and colder within 12 hours.

29.80 or below, and falling rapidly

south to east

Severe storm of wind and rain imminent. In winter, snow or cold wave within 24 hours.

29.80 or below, and falling rapidly

east to north

Severe northeast gales and heavy rain or snow, followed in winter by cold wave.

29.80 or below, and rising rapidly

going to west

Clearing and colder.

Note: A barometer should be adjusted to show equivalent sea-level pressure for the altitude at which it is to be used. A change of 100 feet in elevation will cause a decrease of 1 ⁄10 inch in the reading.